The research program of the Virus Ecology Unit (VEU) is focused at understanding the drivers of virus emergence. Although tremendous progress has been made over the last decade in prevention and treatment of infectious diseases, prophylactic or therapeutic options are not available for most emerging and newly emerging diseases, or would not easily become available to resource poor areas where these outbreaks often occur. Currently, our best hope to prevent or intervene in future outbreaks of most emerging viruses lies in the potential to efficiently block cross-species, zoonotic and human-to-human transmission. The main objectives of the VEU research program aim at the identification of the underlying biotic or abiotic changes in virus-host ecology that allow these emerging viral pathogens to cross the species barrier. Recognizing both the strengths and weaknesses of a unilateral focus on field research on one hand and experimental research on the other, we set out to combine the best of both approaches in one research program, where we aim to identify drivers of cross-species transmission from data gathered in the field and model these drivers under experimental conditions in the lab. For a wide variety of novel emerging infectious viruses (e.g., Nipah virus, Ebolavirus, MERS-CoV), no prophylactic or therapeutic intervention strategies are currently available to prevent or contain outbreak events10. In addition, very limited information is available on the route of zoonotic and human-to-human transmission for most of these viruses. Currently, our best hope to prevent or intervene in future outbreaks of these viruses lies in the potential to efficiently block transmission and thereby spread of the outbreak. In order to efficiently establish prevention strategies, detailed knowledge on mechanisms of pathogenicity and transmission (contact transmission, fomite transmission, aerosol transmission, foodborne or vertical transmission) in the context of abiotic (temperature, humidity, airflow) and biotic (routes of transmission, immune status, receptor distribution, amount of shed virus) factors is needed. A more comprehensive understanding of transmission events is likely to make an important contribution to the control of emerging zoonotic infections.